1. Field of the Invention
The present invention relates generally to an apparatus for controlling a tape speed and, more particularly, is directed to an editing apparatus capable of controlling a plurality of video tape recorders in a so-called dynamic motion control system so that a slow motion picture, a quick motion picture or a combination of the slow motion picture and the quick motion picture reproduced by the video tape recorder can be edited on a video tape.
2. Description of the Prior Art
With the spread of video tape recorders and video disk apparatus, a demand for software such as a more sophisticated video tape has been increased. To meet the above-mentioned demand, an editing apparatus is proposed to edit (cut, wipe and dissolve) a desired event by using a plurality of video tape recorders so that the video tape is edited. An official gazette of Japanese laid-open patent application No. 60-202590 discloses this kind of editing apparatus which combines not only desired events but also a slow motion picture and a quick motion picture by a so-called dynamic motion control (DMC) system such as causing a tape of a recording video tape recorder and/or player to run at a running speed different from the normal running speed.
Various dynamic motion control systems are known. According to one of the known systems, a plurality of events are designated within one edition unit and a desired tape running speed can be chosen at each event. In this prior-art system, the recording video tape recorder is operated at a normal tape running speed and commands are supplied to the reproducing video tape recorder (hereinafter, referred to as a player for simplicity) so that the running speed becomes equal to running speeds S.sub.0, S.sub.1, S.sub.2 and S.sub.3 provided as parameters of a tape driven by the player designated at times T.sub.0, T.sub.1, T.sub.2 and T.sub.3, provided as parameters, within one edition unit (from edit-in point T.sub.0 to edit-out point T.sub.N) as, for example, shown in FIG. 1. The running speed S of the tape driven by the player is, as a result, varied substantially stepwise except transition times .DELTA.T.sub.1, .DELTA.T.sub.2 and .DELTA.T.sub.3 of the player. Hence, this prior-art system is called "a control system based on [step mode]".
In the prior-art editing apparatus for carrying out the control based on the step mode, it is frequently observed that the motion speed of the edited picture suddenly changes at a certain time, thereby causing the viewer to feel confused. In order to remove the above-mentioned defects, one proposal is made, in which the running speed of the tape drive by the player is varied little by little by increasing the number of events within the edition unit interval. When the number of events is increased, a large number of a pair of parameters {time T.sub.i and running speed S.sub.i of tape to be reproduced where i=0, 1, 2, . . . } have to be designated, which method is very complicated in practice.
Further, there exists an editing apparatus of a type which can successively vary a running speed of a tape driven by a player in an analog fashion by its manual dial. This type of editing apparatus cannot reproduce the state that the tape running speed was varied. The problem is then presented that the effect achieved by the change of the tape running speed in some edited video program cannot be effectively utilized to edit other video programs.